创建design-demo项目

项目代码：https://gitee.com/java_wxid/java_wxid/tree/master/demo/design-demo
项目结构如下（示例）：
在这里插入图片描述

创建UserController

代码如下（示例）：

package com.example.designdemo.controller;

import com.example.designdemo.pojo.TicketParam;
import com.example.designdemo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 19:26
 * @Description:
 */
@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @PostMapping("/ticket")
    public Object getTicket(@RequestBody TicketParam ticketParam) {
        return userService.getTicket(ticketParam);
    }

}

创建UserService

代码如下（示例）：

package com.example.designdemo.service;

import com.example.designdemo.pojo.TicketParam;


/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 9:28
 * @Description:
 */

public interface UserService {

    Object getTicket(TicketParam ticketParam);
}

创建UserServiceImpl

代码如下（示例）：

package com.example.designdemo.service.impl;

import com.example.designdemo.handler.SuggestRequirementHandlerProcess;
import com.example.designdemo.pojo.TicketParam;
import com.example.designdemo.pojo.UserInfo;
import com.example.designdemo.service.UserService;
import com.example.designdemo.ticket.builder.CompanyTicketBuilder;
import com.example.designdemo.ticket.builder.PersonalTicketBuilder;
import com.example.designdemo.ticket.builder.TicketBuilder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private SuggestRequirementHandlerProcess suggestRequirementHandlerProcess;

    //因为这部分是需要查询 缓存（如果缓存没有，需要查库）不应该写到 service层，但是为了代码书写简便
    //这部分我模拟在service 层。
    private UserInfo getUserInfo(String username) {
        return new UserInfo();
    }

    public Object getTicket(TicketParam ticketParam) {
        TicketBuilder builder = null;
        String bankInfo = null;
        if(ticketParam.getBankInfo() != null) {
            bankInfo = "from 3rd party interface check.";
            builder = new CompanyTicketBuilder();
        } else {
            builder = new PersonalTicketBuilder();
        }
        builder.setParam(ticketParam.getAccount(), ticketParam.getTitle());
        String content = "from config center";
        String product = "from db";
        builder.setContent(content);
        builder.setProduct(product);
        builder.setBankInfo(bankInfo);
        // 详细的逻辑细节控制以及从配置中心或者是db中获取的逻辑步骤就是简单的 crud，自己明白即可
        return  builder.buildTicket();
    }
}

创建TicketBuilder

代码如下（示例）：

package com.example.designdemo.ticket.builder;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/29 21:29
 * @Description:
 */
public abstract class TicketBuilder<T> {
    public abstract void setParam(String account, String title);

    public abstract void setContent(String content); // 配置中心 或 DB 或缓存
    public abstract void setProduct(String product); // db
    public void setBankInfo(String bankInfo){}; //需要校验的，校验通过才能设置

    public abstract T buildTicket();
}

创建PersonalTicketBuilder

代码如下（示例）：

package com.example.designdemo.ticket.builder;


import com.example.designdemo.ticket.TicketConstant;
import com.example.designdemo.ticket.pojo.PersonalTicket;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/29 21:29
 * @Description:
 */
public class PersonalTicketBuilder extends TicketBuilder<PersonalTicket> {

    private PersonalTicket personalTicket = TicketConstant.personalTicket.clone(); // new 关键字 改成clone的形式，只clone我们的
    // 不可变部分。对于可变部分和自定义用户提交部分，不进行clone

    @Override
    public void setParam(String account, String title) {
        personalTicket.setTitle(title);
        personalTicket.setAccount(account);
    }

    @Override
    public void setContent(String content) {
        personalTicket.setContent(content);
    }

    @Override
    public void setProduct(String product) {
        personalTicket.setProduct(product);
    }

    @Override
    public PersonalTicket buildTicket() {
        return personalTicket;
    }
}

创建CompanyTicketBuilder

代码如下（示例）：

package com.example.designdemo.ticket.builder;


import com.example.designdemo.ticket.TicketConstant;
import com.example.designdemo.ticket.pojo.CompanyTicket;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/29 21:29
 * @Description:
 */
public class CompanyTicketBuilder extends TicketBuilder<CompanyTicket> {

    private CompanyTicket companyTicket = TicketConstant.companyTicket.clone(); // new 关键字

    @Override
    public void setBankInfo(String bankInfo) {
        companyTicket.setBankInfo(bankInfo);
    }

    @Override
    public void setParam(String account, String title) {
        companyTicket.setTitle(title);
        companyTicket.setAccount(account);
    }

    @Override
    public void setContent(String content) {
        companyTicket.setContent(content);
    }

    @Override
    public void setProduct(String product) {
        companyTicket.setProduct(product);
    }

    @Override
    public CompanyTicket buildTicket() {
        return companyTicket;
    }
}

创建CompanyTicket

代码如下（示例）：

package com.example.designdemo.ticket.pojo;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/29 21:29
 * @Description:
 */
public class CompanyTicket implements Cloneable{
    private String type;
    private String footer;

    private String content; //配置中心 或者 DB里边获取。（缓存里获取，只不过如果万一DB 或配置中心有修改，需要同时更新缓存）
    private String product; //大部分情况db里获取（缓存里是有一些热门产品的）
    private String bankInfo; //校验我们的银行卡信息（通过我们的第三方银行相关接口进行的校验）

    private String account;
    private String title;

    public String getFooter() {
        return footer;
    }

    public void setFooter(String footer) {
        this.footer = footer;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getAccount() {
        return account;
    }

    public void setAccount(String account) {
        this.account = account;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public String getProduct() {
        return product;
    }

    public void setProduct(String product) {
        this.product = product;
    }

    public String getBankInfo() {
        return bankInfo;
    }

    public void setBankInfo(String bankInfo) {
        this.bankInfo = bankInfo;
    }

    @Override
    public CompanyTicket clone() {
        CompanyTicket companyTicket = null;
        try {
            companyTicket = (CompanyTicket) super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return companyTicket;
    }
}

创建PersonalTicket

代码如下（示例）：

package com.example.designdemo.ticket.pojo;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/29 21:29
 * @Description:
 */
public class PersonalTicket implements Cloneable{
    private String type;
    private String footer;

    private String content; //配置中心 或者 DB里边获取。（缓存里获取，只不过如果万一DB 或配置中心有修改，需要同时更新缓存）
    private String product; //大部分情况db里获取（缓存里是有一些热门产品的）

    private String account; // 接口入参获取
    private String title;  // 接口入参获取

    public String getFooter() {
        return footer;
    }

    public void setFooter(String footer) {
        this.footer = footer;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getAccount() {
        return account;
    }

    public void setAccount(String account) {
        this.account = account;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public String getProduct() {
        return product;
    }

    public void setProduct(String product) {
        this.product = product;
    }

    @Override
    public PersonalTicket clone() {
        PersonalTicket personalTicket = null;
        try {
            personalTicket = (PersonalTicket) super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return personalTicket;
    }
}

创建TicketConstant

代码如下（示例）：

package com.example.designdemo.ticket;


import com.example.designdemo.ticket.pojo.CompanyTicket;
import com.example.designdemo.ticket.pojo.PersonalTicket;

public class TicketConstant {
    // 保存只具有公共属性的对象，供clone使用。
    public static PersonalTicket personalTicket = new PersonalTicket();
    public static CompanyTicket companyTicket = new CompanyTicket();

    static {
        personalTicket.setType("type");
        personalTicket.setFooter("footer");
        companyTicket.setType("type");
        companyTicket.setFooter("footer");
    }
}